There's nothing worse than brushing your teeth, getting cozy in your PJs, laying your head down on your pillow—and then not being able to fall asleep. Sadly, this is an all-too-common problem; about one in four Americans develop insomnia each year, which means tens of millions of people are going through their day sleep-deprived and groggy.

And according to new research, it's not just fatigue we should be concerned about. The study, which was published in the American Heart Association's journal Circulation, says that insomnia could be putting your heart health at risk, too.

According to the lead author Susanna Larsson, Ph.D., previous studies have linked insomnia and heart disease but were unable to decipher whether the relationship was causal or correlative. In other words: Did the insomnia cause the heart disease or were the two just randomly associated?

This study used a technique called Mendelian randomization, which uses genetic information to reduce bias and prove causation. The authors collected information from 1.3 million participants, with or without heart disease, and were able to show that specific genetic variants for insomnia are directly associated with an increased likelihood of developing coronary artery disease, stroke, and heart failure.

And seeing as heart disease is the No. 1 cause of death globally, this is definitely motivation to get to the root cause of insomnia. Larson, who currently works as an associate professor of cardiovascular and nutritional epidemiology at the Karolinska Institutet in Stockholm, says, "It's important to identify the underlying reason for insomnia and treat it. Sleep is a behavior that can be changed by new habits and stress management."